1. Field of the Invention
The present invention relates to a control apparatus for a cylinder injection internal combustion engine with high-pressure fuel pump, and more particularly to a control apparatus for a high-pressure fuel system of a cylinder injection internal combustion engine including a variable valve mechanism in a cam shaft which drives a high-pressure fuel pump.
2. Background Art
In cylinder injection internal combustion engines, after the fuel pressure has been raised to a target value, the cylinder injection is performed. In this case, the control apparatus for the cylinder injection internal combustion engine with high-pressure fuel pump regulates the discharge amount of the high-pressure fuel pump of the high-pressure fuel system according to fuel injection amount and fuel pressure. Also, the injector control apparatus of the control apparatus for a cylinder injection internal combustion engine corrects the valve opening time of the injector according to fuel pressure to regulate the injection amount.
In this high-pressure fuel system, when the fuel pressure pulsation in the fuel rail increases, there occurs a difference between the detection value from a fuel pressure sensor and the fuel pressure during injection. As a result, the injector fuel pressure correction does not work properly, so the injection amount may deviate from stoichiometry, causing exhaust deterioration. Further, due to the deviation of injection, a large pulsation may occur; this is a factor in reduced reliability of the high-pressure fuel system.
As a related art technique of preventing occurrence of such pulsation to regulate the fuel pressure to a target value, there has been disclosed a technique (for example, JP Patent No. 3562351 mentioned below) of feeding back a detected fuel pressure value to the pump discharge amount. Further, JP Patent No. 3562351 deals with variable valve mechanism; a cam angle sensor detects a cam phase, and the detected value is used as a control element for pump control, thereby preventing occurrence of discharge amount variation based on cam phase variation.